Those costumes are designed by Tada Kaie, a big name cosplayers
(called "layers" now-a-days) whose day job is costume design and making.
She had appeared in Kikuko's consert last winter cosplaying as Sailor Venus.
She is also a regular atttendant of Anime Expo in LA, together with her
partner in crime Barbie Tsukino, another big name layer who was also in
Kikuko's concert cosplaying Sailor Moon.